Closures for pressurized containers have generally been multicomponent devices. For example, sparkling wines, such as champagne, sekt or spumante have often been sealed with cork closures wired onto the neck of the bottle. These natural cork closures, besides being expensive, require a number of steps for their insertion and additional steps for placing the wire retainer over the cork and around a ring on the neck of the bottle. Such a closure adds to the cost of the product sold.
One problem with closures for sparkling wines which use wire retainers is their well-known propensity to suddenly blow off the end of the bottle after the wire retainer is removed. This may tend to happen especially if the wine is not chilled sufficiently or if it is shaken or jarred; in either case the high pressures developed beneath the cork, be it natural or plastic, are sufficient to discharge the cork from the bottle at quite high velocities. Damage to persons and property often results from the sudden, unexpected discharge of the cork.
In U.S. Pat. No. 3,946,891 to Picoy, et al., a flexible plastic cap for use on pressurized containers which eliminates the wire retainer is disclosed. The cap in Picoy includes an inner shank, an outer cap and a depending skirt portion having internal rib portions for engagement under the ring on the neck of the bottle. However in Picoy the cap relies upon circumferential expansion of the skirt material to permit the rip portion to pass over the outwardly extending ring or band on the bottle. Thus the thickness of the ring around the neck of the bottle and the thickness of the rib portion on the skirt are limited by the resilient character of the material from which the cap is made. If the circumferential stretching is too great, the skirt may be permanently deformed so that the rib portion does not fully engage the lower surface of the rim of the bottle. If the ring and/or ribs are not thick enough, the cap may blow off the bottle. Further, even if the plastic material from which the cap is made would tend to return to its fully unstressed state, because of the time lag involved the cork may be blown off the end of the bottle before such contraction has been completed.
The following patents may also be of interest: U.S. Pat. Nos. 4,162,736; 4,057,160; 4,033,472 and 3,809,370.